The development of improved implantable devices and biomaterials requires knowledge of their in vivo behavior. However, little is known about the actual loads borne by implanted devices in vivo. Direct measurement of these loads would provide extremely valuable information, for the improvement of device designs, and for the rapid rehabilitation of individuals in which devices have been implanted. Multi-channel telemetry systems, combined with strain gauges, can provide this information. Miniaturized, implantable, wireless transmitters provide several advantages over conventional hard wiring: freedom from the constraints of wires; reduced risk of infection; and less discomfort for animal subjects. Long term telemetered monitoring also produces higher quality data from each subject, which can reduce the number of animals required for statistical analysis. The goal of this proposal is to produce multi-channel strain gauge telemetry systems capable of reliable, long term implantation. Highly integrated microelectronic components will be utilized to produce low power, pulse width modulated transmitters. A microprocessor based receiver will demodulate, display, and store the telemetered data. Phase I is focused on the electronics, with the production of working, well tested prototypes. Phase II includes hermetic packaging, transcutaneous powering, and in vivo testing of an FDA approved spinal implant. An immediate demand for these new systems from universities, medical schools, and pharmaceutical companies is anticipated.